This invention relates generally to a circuit for increasing the operating range of circuit elements and a method of operation whereby high breakdown capabilities may be obtained using circuit elements having low breakdown characteristics. More particularly, this invention relates to a circuit and method of operation for increasing the operating range of circuit elements, such as semiconductor elements, so that high breakdown capabilities may be obtained using semiconductor elements having low breakdown characteristics.
Although high breakdown circuit elements, such as transistors, have heretofore been provided, they occupy excessive semiconductor areas because of the large depletion regions required to support higher operating voltages. For example, linear elements must handle a wide signal range and may operate with 36 to 45 volts, or higher, voltage swings. The relatively high supply voltages required for operation dictate that all, or substantial portions, of, the semiconductor structures be large in size to provide large depletion regions to support the high operational voltages utilized. In contrast, digital elements may typically operate from a 5 volt supply, high operational voltage swings are not encountered, and the structure need not provide large depletion regions. Accordingly, linear element structures may have to be 4 or more times the physical size of digital element structures so that selected linear elements have the requisite large depletion regions for high breakdown operational characteristics.
Thus there is a need for a circuit for increasing the operating range of circuit elements whereby high breakdown capabilities may be obtained using circuit elements having low breakdown characteristics.